Rearranging Equations with Factorials?That was really helpful, thank you so much! Just one question - what happens if the numbers are much larger than those where you know the factors of 20? I'm sufficiently familiar with multiplication tables to know the factors of 20 and figure out (n) (n-1) = 20. If the numbers were less friendly (or I suppose less easily predicatble), then is there another solution? I guess what I'm trying to ask is, can you work backwards from these equations to solve for much larger/less tidy numbers?